A zone that keeps watering is usually a valve problem
If the controller says the zone is off but water continues flowing, the irrigation valve may not be sealing.
Debris inside the valve
Small debris can prevent the diaphragm from closing completely. Internal wear or a damaged diaphragm can cause the same symptom.
Electrical versus hydraulic problems
If disconnecting controller power does not stop the water, the problem is probably hydraulic rather than a controller command.
Protect the property
If the zone will not stop, shut off the irrigation water supply until the problem can be repaired. Continuous watering can flood landscaping and waste significant water.
Our sprinkler valve repair page covers valve and solenoid service.
Manufacturer resource
Hunter notes that debris or diaphragm damage can prevent an irrigation valve from closing. Hunter valve-not-closing guidance
First determine whether the controller is still commanding the zone
Turn the controller to its off position. If the zone continues to flow, the valve is likely being held open mechanically rather than by a normal watering program. If shutting the controller off stops the zone, inspect programming for duplicate start times or unintended schedules.
Mechanical causes
Debris between the diaphragm and valve seat is a common cause. A damaged diaphragm, loose bleed screw or solenoid that is not fully tightened can also prevent complete closure. Do not disassemble a pressurized valve.
Related guides
See sprinkler valve symptoms and backflow preventer leak troubleshooting.
